This invention relates generally to inspecting a pipe for anomalies, and more specifically to inspecting a pipe using a reflected component of an input waveform.
To maintain substantial fluid flow through a pipe, internal pipe characteristics need to be monitored so that defects, obstructions, and other anomalies in the pipe can be detected and repaired efficiently, or in the case of quality assurance testing, discarded. In addition to manufacturing defects and other anomalies, such as obstructions, affecting fluid flow in the pipe, the pipe may bend and/or buckle in response to changes in pressure, such as result when pipes are laid underwater. Frequently, companies must endure substantial monetary costs and schedule delays due to the detection and repair of these pipe anomalies.
In some conventional pipe inspection systems, an internal, invasive device crawls the length of the pipe to inspect it for anomalies. This device, typically referred to as a xe2x80x9cpigxe2x80x9d, poses a serious blockage to the normal fluid flow through a pipe. A pig also may require several days for the inspection of a lengthy pipe. Furthermore, the amount of data a pig can record, the life of its battery, and the wear of its components from crawling the pipe all limit the usefulness of the pig.
Measuring the acoustic signature of a pipe is another technique used to detect pipe anomalies. This technique sometimes involves hitting the pipe on its side with a hard object, such as a hammer, and then measuring the acoustic signature of the pipe. Anomalies often alter the acoustic signature of a pipe as compared to a pipe with no such anomalies. However, the magnitude of the anomaly that may be detected is dependent upon the wavelength of the waveform transmitted along the pipe, and sound waves generally have longer wavelengths than some other waveforms. Therefore, this technique typically fails to detect smaller-sized anomalies in a pipe and is relatively ineffective in pre-installation quality assurance testing.
Pulse propagation may also be used to detect pipe anomalies. According to one technique, two pulses are transmitted along the pipe from opposing locations towards an intersecting location. The pulses intersect and are each modified by collision with the oppositely directed pulse. A receiver is positioned at the intersecting location and, after receiving the modified pulses, analyzes at least one indicator characteristic of one of the modified pulses to determine whether an anomaly exists between the receiver and the corresponding transmitter. However, this technique usually requires two separate transmitters and a separate receiver, each of which increases the costs associated with detecting anomalies. Also, pulse propagation analysis may further require inserting the receiver into a location in the pipe not normally open for device placement.
Another conventional approach is an ultrasonic guided wave inspection technique that uses stress waves, such as Lamb waves. Since Lamb waves are typically guided along the pipe, lateral spreading of the energy associated with these waves does not usually occur and the propagation is essentially one-dimensional. For this reason, Lamb waves normally propagate over longer distances than other types of waves, such as bulk waves. Unfortunately, at least two modes typically exist at any frequency for Lamb waves. Furthermore, the modes are generally dispersive, which means that the shape of the propagating waveform varies with distance along the pipe. Consequently, the signals typically suffer from signal-to-noise problems and are difficult to interpret.
Accordingly, it is desirable to produce a system that is capable of detecting an internal characteristic of a pipe in a non-invasive fashion. It is also desirable to be able to inspect a pipe faster than currently possible, as well as to be able to accurately detect smaller-sized anomalies in a pipe. It is further desirable to provide improved quality assurance testing prior to pipe installation.
Briefly, the invention relates to a system and method for inspecting a pipe. In one embodiment, the invention provides a system for detecting and characterizing an anomaly in a pipe. In another embodiment, the invention provides a system that can also determine the longitudinal path/shape of the pipe. With a starting point and the longitudinal shape of the pipe, a further embodiment of the invention can also determine the location of a pipe buried underground or even underwater.
According to one preferred embodiment, the system includes a processor, an analyzer, and a wave launcher. In an alternate embodiment, the analyzer, wave launcher, and processor are incorporated into a single unit, thereby eliminating the external connections between the devices. In yet another embodiment, an integrated analyzer and an integrated wave launcher are located inside an end portion of the pipe to be inspected. The wave launcher communicates with the pipe, and is adapted to transmit an input waveform having a selected input energy along a longitudinal axis of the pipe. Examples of the type of input waveform include, but are not limited to, an electromagnetic waveform, a wideband waveform, and an acoustic waveform. Further examples of input wideband waveforms include, but are not limited to, a chirp waveform, a spread spectrum waveform, a wavelet waveform, and a solitons waveform. The wave launcher is further adapted to receive a reflected component of the input waveform having a characteristic reflected energy. An example of the wave launcher includes an antenna adapted to transmit the input waveform along a longitudinal pipe.
In one embodiment, the wave launcher transmits an input waveform having a selected cutoff frequency. The cutoff frequency is a frequency below which no input waveform propagates. This cutoff frequency is the minimum frequency needed to propagate the first mode of the input waveform along the longitudinal axis of pipe.
The invention can also be used to inspect a pipe prior to laying the pipe. This inspection is typically used as a quality control measurement. For example, the operator can inspect the pipe for a manufacturing defect, an anomaly that arose during transportation of the pipe, such as a rock, or for an anomaly that arose due to the age of the pipe, such as rust. Furthermore, the processor of the inspection system can display details to particular manufacturing tolerances that the pipe fails to meet.
In a further embodiment, the processor of the inspection system is adapted to determine an axial curvature of the pipe as the pipe is being laid. Moreover, the determination can be repeated multiple times to enable the processor to provide a substantially real-time measurement of curves in the pipe. In one embodiment, the inspection system displays a graphical representation of the substantially real-time measurement of the pipe curvature, along with information regarding resultant mechanical stresses on the pipe to an operator. The operator can use such information, for example, to guide a pipe installation process to avoid potentially damaging mechanical stresses being inflicted on the pipe.
In a further embodiment, the pipe inspection system is adapted to transmit a microwave waveform into pipe to dissolve an anomaly. In a related embodiment, the pipe is coated with a microwave sensitive coating and/or wrap that is adapted to heat in response to the microwave waveform.
In another embodiment, the pipe inspection system includes a wave launcher, an analyzer, a clamp, and an umbilical. The wave launcher is adapted to transmit an input waveform having a selected input energy along a longitudinal axis of a first section of pipe. The wave launcher is also able to receive a reflected portion of the input waveform from the pipe. The analyzer communicates with the wave launcher and is adapted to generate the input waveform and to receive the reflected portion of the waveform from the wave launcher. The clamp mechanically connects with the analyzer and temporarily connects the first section of the pipe with the second section of the pipe. An operator uses the umbilical to move the wave launcher and/or the analyzer from the first section of the pipe to the second section of the pipe to enable the wave launcher to transmit the input waveform along the longitudinal axis of the first section of the pipe and the second section of the pipe.